1. Field of the Invention
This invention relates to a wiper device which wipes off raindrops, dust and the like on a surface of a windshield of an automobile for example, and especially, relates to a wiper pivot for moving a wiper arm with oscillatory motion in a prescribed wiping area.
2. Description of the Prior Art
Heretofore, there has been used a wiper device having a construction shown in FIG. 5 for example.
A wiper device 101 shown in FIG. 5 is provided with a motor 102 and wiper pivots 103 for making a wiper arm (not shown) wipe the windshield surface in the prescribed angular range, and is provided with a motor arm 105 which is fixed to an output shaft of the wiper motor 102 for converting rotary motion of the wiper motor 102 into reciprocative motion, a pivot arm 107 fixed to a pivot shaft 106, a first connecting rod 108 for giving the pivot arm 107 an oscillatory motion by interlocking the pivot arm 107 with said motor arm 105 and a second connecting rod 109 for interlocking each of pivot arms 107 of respective wiper pivot 103.
Said wiper pivot 103, as shown in FIG. 6 and FIG. 7, is provided with the pivot shaft 106 which is fixed with the pivot arm 107 at one end thereof and has a screw portion 106a to fix the wiper arm (not shown) by screw clamping, for converting reciprocative motion of the first connecting rod 108 into oscillatory motion of the wiper arm. A pivot holder 110 supports said pivot shaft 106 in rotatable state, with a wave washer 111 lying between the pivot arm 107 and the pivot holder 110 for preventing a rattling between the pivot arm 107 and the pivot holder 110 by the elastic force in the axial direction and also with a stop ring 113 which has been fitted into a groove 106b of the pivot shaft 106 so as not to come out from said pivot holder 110 through a washer 112 after inserting the pivot shaft 106 into the pivot holder 110.
Said wiper device 101 has a function to convert the rotary motion of the wiper motor 102 into the reciprocative motion by means of the motor arm 105 and the first connecting rod 108, and the reciprocative motion of said first connecting rod 108 is converted into the oscillatory-rotational motion of the wiper pivots 106 by the first connecting rod 108, the second connecting rod 109 and the respective pivot arms 107, so that raindrops, dust and the like existing on a surface of the windsheild are wiped off by the oscillatory motion of the respective wiper arm in the prescribed angular range.
In the wiper pivot 103 of the conventional wiper device 101 described above, there is a gap between the pivot holder 110 and the pivot arm 107 when the pivot shaft 106 is assembled into the pivot holder 110. Therefore, the pivot holder 110 is energized from the pivot arm 107 by setting the wave washer 111 into said gap in order to prevent a rattling caused by said gap when the wiper pivot 103 is mounted on a vehicle body. However, since said wave washer 111 does not have a waterproof function, rain water and the like may enter into the pivot holder 110 through the said gap, and rust formed on the pivot shaft 106 sometimes obstructs the rotation of said pivot shaft 106.